The present invention relates to composite containers for food products, and more particularly, to one piece removable film labels applied to the outer surface of composite containers.
In the packaging of perishable food products, a container is required that is rigid enough to retain its shape when subjected to internal pressure produced in the container while tightly sealing the food product to protect against deterioration, leakage, and contamination. Thus, perishable food products are often packaged in composite tubular containers that are sealed at both ends. In particular, refrigerated dough products typically are packaged in spiral wound containers which allow access to the dough products via the unwinding of the spiral seam. These containers rely mainly on the label to provide enough strength to retain the pressurized contents of the package until consumers use the product. The consumer peels the label from the package, allowing the container to open along the spiral seam, revealing the dough product. The tubular portion of these containers conventionally includes three separate plies or sets of plies.
First, at least one structural body ply made of paperboard material is included, which is formed into a tubular structure by wrapping a continuous strip of body ply paperboard material around a shaping mandrel. The body ply strip may be spirally wound around the mandrel or passed through a series of forming elements so as to be wrapped in a convolute shape around the mandrel. The tube is then cut into predetermined lengths at the downstream end of the mandrel and fitted with end closures to complete the container.
Second, these containers typically include a liquid impermeable liner ply adhered to the inner surface of the paperboard body ply. The liner ply seals the food product, such as dough, within the container and also prevents liquids, which may possibly contaminate the food product, from entering the container. Some liner plies are also gas impermeable, so as to not only prevent food product odors from escaping the can, but also prevent atmospheric air from entering the container and spoiling the food product. Thus, while the purpose of the body ply is to provide necessary structural properties to the container, the liner ply provides barrier properties necessary to protect and maintain the perishable food product.
Finally, a label ply, which is typically a paper-based ply, is included and adhered to the outer surface of the paperboard body ply. The label ply serves two primary functions. First, a composite can label is a source of information. The label carries the graphical matter that conveys product information, instructions, and regulatory compliance information. The label is also preferably decorative and aesthetically pleasing to the consumer, which enhances shelf appeal and increases consumer interest in the food product. The graphics included on conventional paper labels are either rotogravure or flexographically printed and, to protect the inks used in the label printing process, may require overlacquers over the inks. However, the overlacquers may not absorb evenly into the paper and thus create labels having poor aesthetic appearance.
The second function of the label ply is to provide some physical characteristics to the composite can. The coefficient of friction of the label ply is important because the lower the coefficient of friction, the easier the composite container is handled. The container is often routed along conveyor lines and chutes as it manufactured, filled and then shipped. Thus, a composite container with a high coefficient of friction can create inefficiencies in product packaging and increase the cost of packaging the food product, while a container with a low coefficient of friction can minimize such inefficiencies and costs.
Also, the wet strength of the label ply can be an important factor in composite container design. If the container is exposed to moisture and the paperboard body ply gets wet, the strength of the can is compromised. Such moisture is sometimes encountered during storage and shipping. At other times, condensation may form on the surface of the can if the can is refrigerated or otherwise exposed to cold temperatures and then moved to a warmer, humid environment. If the wet strength of the label ply is low, then the label will provide little additional relief to the body ply from premature rupturing of the container. Accordingly, a foil layer is often used as part of the label to add strength.
The wet strength of label plies is especially important when the plies are used in conjunction with composite cans for dough. Composite dough cans are designed differently from other composite containers such that they can be opened by forcefully striking the container against a sharp surface, such as the edge of a kitchen counter, or by pressing the seam of the container with a utensil. The edges of the body ply strip are typically abutted and held together with an unadhered or lightly adhered joint or seam. The label ply is thus designed to provide a substantial component of the total strength of the can necessary to prevent the can from prematurely opening. Accordingly, when the label ply or other outer wrapper is completely removed, the internal pressure of the dough and the force of impact against a sharp edge or pressure from a utensil causes the body ply seam to separate, thus allowing the dough product to be removed from the can. In some xe2x80x9cself-openingxe2x80x9d cans, it may not be necessary to provide external pressure after removing the label. In addition, dough containers are typically stored in refrigerated conditions. This type of storage is usually at high humidity. During storage the label material is exposed to moisture which can weaken the paperboard ply. This makes the strength of the label ply even more critical because if the label ply is exposed to moisture and has a low wet strength, as is the case with most paper labels, the container may prematurely rupture. In addition, the label is torn away to open the container, as discussed above. The line along which the label is torn, however, can occasionally deteriorate into a separation of the paper ply or plies which can leave some label material on the outer surface of the body ply. This problem, known as xe2x80x9cfeathering,xe2x80x9d can cause difficulties in opening the container.
As an alternative to conventional paper labels, several prior patents have mentioned the possible use of labels for dough cans or easy-open containers which are made of polymeric film. For example, U.S. Pat. No. 3,981,433 to Thornhill et al. discloses a composite container for dough with a peelable outer reinforcing or wrapper layer. According to the ""433 patent, the peelable outer wrapper layer can be formed of paper, metal foil, or a suitable synthetic plastic material, such as polyethylene adhesively bonded to the outer surface of a fibrous body wall layer by way of a separately applied polyvinyl alcohol adhesive. U.S. Pat. No. 4,235,341 to Martin et al. discloses a dough container having inner and outer plies over a fiber board body ply. According to one embodiment the inner ply is a low density polyethylene film. The outer ply is described as a thermoplastic paper film. U.S. Pat. No. 5,076,440 to Drummond discloses a dough container having a label which can be of plastic film. U.S. Pat. No. 5,084,284 to McDilda et al. discloses a dough container with a label that can be made of a plastic film. U.S. Pat. No. 5,326,023 to Rice et al. discusses a dough container wherein the label layer is formed of a xe2x80x9csuitable biaxially oriented polymer film.xe2x80x9d The film discussed therein comprises a polypropylene film.
These films could theoretically provide improved wet strength for dough can labels. However, the types of films potentially usable for dough can labels are limited. The label must be fairly easily removable so that the consumer can open the container to obtain the dough product inside. Accordingly, the type of film used must be easily separable from the body ply and easily graspable by the consumer to allow removal. Also, to properly open dough cans, the label is preferably completely removed or at least completely torn along a predetermined line so that the spiral seam of the body ply can be completely separated. Accordingly, the film label must be of such a type that it can be easily and completely removed from the container without feathering.
Some films have predictable tear characteristics; i.e., they tear in a predictable direction, and thus could be useful for dough can labels because of the potential to completely remove the label and expose the body ply seam. However, films having predictable tear characteristics may not provide the strength necessary to prevent the can from rupturing. More specifically, films having predictable tear characteristics typically are susceptible to stretching over time, known as xe2x80x9ccreepxe2x80x9d, as a result of pressure within the can attempting tocause expansion of the body ply seam, which undermines the strength of the label and the overall strength of the container. In addition, not all polymeric films have been proven to be capable of providing a peelable bond to a paperboard container, as is preferred in dough containers.
Accordingly, it would be desirable to provide a decorative composite container for expansible food products with a removable film label having improved label ply wet strength compared to paper labels and a decreased coefficient of friction, and could be peelably removed from the container without feathering. The label would preferably have sufficient strength and dimensional stability to be usable as a structural member of a dough container, but yet also be sufficiently tearable to allow easy opening of the container.
These and other needs are provided, according to the invention, by a decorative composite container for consumer products having a tubular body ply and a film label ply which is adhered to the body ply. The film label ply comprises a polymeric film or laminate having inner and outer layers permanently bonded together, wherein one of the layers is formed of a polymeric material having predictable tear characteristics and the other of the layers has a high resistance to creep in the circumferential direction. As an example, a film label ply having an inner layer formed of oriented high density polyethylene and an outer layer formed of polyethylene terephthalate advantageously has both predictable tear characteristics due to the oriented polyethylene and a high resistance to creep because of the polyethylene terephthalate. Thus, a highly desirable removable label for composite containers is provided which solves all of the problems of conventional labels outlined above.
In particular, a tubular composite container for advertising products contained therein to consumers is provided wherein the tubular body ply is formed of paperboard material having inner and outer surfaces and opposed ends. The film label ply is wrapped around the outer surface of the tubular body ply and is tearable away from the tubular body ply so that the body ply can be separated and the container opened. As noted above, the film label ply comprises a polymeric film or laminate having inner and outer layers. The inner layer is peelably adhered to the tubular body ply and is formed of a polymeric material of a first type, preferably comprising a polyethylene film having predictable tear characteristics. The outer layer of the film label ply is permanently bonded to the inner layer and is formed of a polymeric material of a second type, preferably comprising polyethylene terephthalate having sufficient strength to prevent label ply creep.
Graphical indicia are applied on at least a portion of the film label ply so as to be visible to the consumer. These indicia can be applied on the outer surface of the outer layer of the film label ply or on the inner surface of a transparent outer layer to be visible to a consumer before the container is opened. In addition, indicia such as coupons or games can also be applied to the inner surface of the inner layer of the label so as to be visible to the purchasing consumer after the label is removed. An adhesive such as dextrin is in contact with at least a portion of the inner layer of the film label ply for adhering the label ply to the outer surface of the tubular body ply. The label peel strength should be sufficient to prevent movement of the label so that the container will not open prematurely. The adhesive applied between the inner layer of the label ply and the outer surface of the tubular body ply can be a heat seal coating, a cold seal coating, or even a pressure sensitive adhesive.
The film label ply may be wrapped around the body ply so as to create overlapped edges defining a seam extending between the opposed ends of the tubular body ply. A hot melt adhesive can be applied between the overlapped edges for bonding the overlapped edges, or the adhesive used to adhere the film label ply to the body ply can be used to also adhere the overlapped edges together. The film label ply preferably has predictable tear characteristics, so that a tear in the film label ply initiated by the consumer will follow a path directed by the film label ply. Alternatively, a plurality of perforations or a laser score extending around the outer surface of the tubular body ply may be used for directing a tear in the film label ply.
The decorative tubular composite container according to the invention is preferably for use with dough cans and thus is designed to be opened through a sidewall thereof. Accordingly, the tubular body ply defines a seam at which opposite edges of the paperboard material are abutted and held together with an unadhered or lightly adhered joint or seam. The film label is adhered to the outer surface of the tubular body ply such that as the film label is peeled away from the tubular body ply, the body ply separates to reveal the contents of the container.
The invention provides a decorative multi-ply composite container having graphical indicia applied to the inner layer and/or the outer layer of the film label. The graphical indicia are thus protected from external forces by the outer layer of the film label and/or a layer of overlacquer, depending on which surfaces the graphical indicia are applied. In addition, the wet strength of the film label ply is no less than the strength of the film when not wet. Thus, the multi-ply composite container and polymeric film label of the present invention provide a container having the strength necessary to survive refrigerated storage and withstand the rigors of transportation, yet being easily and completely removable by the consumer.